1. Field of the Invention
The present invention relates to a method for producing a non-aqueous conductive polymer solution containing a π-conjugated conductive polymer.
The present application claims priority from Japanese Patent Application No. 2009-180581, filed on Aug. 3, 2009, the contents of which are hereby incorporated by reference into this application.
2. Description of the Related Art
An aqueous conductive polymer solution formed by dissolving π-conjugated conductive polymer such as polythiophene in water is often used as a coating material for forming a conductive coating film.
In Patent Document 1, a method has been proposed as a method for producing an aqueous conductive polymer solution, in which 3,4-dialkoxythiophene is polymerized by chemical oxidation to produce an aqueous poly(3,4-dialkoxythiophene) solution using an oxidizing agent in the presence of polystyrene sulfonic acid.
Incidentally, it requires a long drying time when forming a conductive coating film by applying an aqueous conductive polymer solution as described above, which makes the productivity of the conductive coating film low.
In order to shorten the drying time, a conductive polymer solution in which water serving as a solvent in the aqueous conductive polymer solution has been substituted with an organic solvent may be used.
As a method for producing a conductive polymer solution, a method has been disclosed in Patent Document 2, in which an organic solvent is added to an aqueous conductive polymer solution, followed by water removal by volatilization using an evaporator.
In addition, a method has been disclosed in Patent Document 3, in which a phase transfer catalyst is added to an aqueous conductive polymer solution to precipitate a mixture containing π-conjugated conductive polymer, a solubilizing polymer and the phase transfer catalyst, followed by the addition of an organic solvent to this mixture.
In Patent Document 4, a method has been disclosed, in which an amine compound is added to an aqueous conductive polymer solution, and the aqueous conductive polymer solution is then concentrated by ultrafiltration, followed by the addition of an organic solvent thereto.
In Patent Document 5, a method in which a conductive polymer solution is spray dried, followed by the addition of an organic solvent, an amine compound and a nonionic surfactant to the resulting solid matter, and a method in which a precipitant and an organic solvent are added to an aqueous conductive polymer solution, and an amine compound and a nonionic surfactant are then added thereto following water removal have been disclosed.